The invention relates to a drill bit for drilling relatively deep holes in rock in the earth's crust. Such a bit is composed essentially of a bit body connectable to a string of pipes and comprises several limbs or bit segments upon which conical cutting elements are freely rotatably journalled, each element having a journal or neck that forms part of the journal bearing, as generally taught in the prior art U.S. Pat. No. 3,307,645. This invention relates more particularly to the problems of sealing, cooling and retaining such bearings.